I’ve never tried to use a device with a CAN bus. I guess that with the proper library and correct device; you could start by following this guide CAN Bus Module Tutorial for Arduino, Raspberry Pi and Intel Galileo . It shows the connection and has a library to work with the CAN module on the Galileo. At the end of the guide this method is tested through the serial monitor. If you have this CAN device as well you can check this method out
The link to the library you posted is not likely going to work, take a look at the summary section; it states that the library is for AVR architecture devices, the Galileo is not AVR.
In the link you posted VSCOM - VSCAN CAN Bus Adapters: USB-CAN I read a little through the user manual. It seems you need to install “can-utils” to be able to use the CAN drivers. The user guide says you can install this from git. What image are you using? I believe the eglibc image already has git installed.
The installation set up for Linux is described in section 1.5 of the user manual. I’d suggest you to go through the installation first, and then you can continue with the rest of the functions.
Let me know if this helps.